Wilms' tumor is a pediatric kidney tumor resulting from the inactivation of both alleles of the Wilms' tumor gene (WT1) located on chromosome 11p13 (Call K M et al., Cell 60: 509, 1990). The non-coding upstream sequence of WT1 (C. E. Camphell et al., Oncogene 9: 583-595, 1994) and the coding region including introns (D. A. Haber et al., Proc. Natl. Acad. Sci. U.S.A., 88:9618-9622 (1991)) have already been reported, and they are expected to be responsible for the growth and differentiation of tumors and the like (D. A. Haber et al., supra).
Based on the association of WT1 with the growth of leukemia cells, the present inventors have found that an antisense oligonucleotide derivative against WT1 suppresses and/or inhibits the growth of leukemia cells (PCT Patent Publication WO96/38176, and T. Yamagami, et al., Blood, 87(7) 2878-2884 (1996)). It is not known, however, if an expression-inhibiting agent of WT1 suppresses and/or inhibits the growth of solid tumors.